1. Field of the Invention
The present invention relates to an image forming apparatus configured so that there is contact between an image carrier belt and a sheet member arranged on a circumferential surface of a transfer roller having a concave section, and to an image forming method.
2. Description of the Related Art
An image forming apparatus for transferring an image formed on an image carrier onto a transfer material is disclosed in, for example, Patent Document 1. The apparatus described in Patent Document 1 is an image forming apparatus in a so-called liquid development system wherein an electrostatic latent image is made visible with a liquid developer that contains toner particles and a carrier liquid. In this apparatus, a print medium (i.e., a transfer material) is held by a holding part disposed on a part of a circumferential surface of an impression cylinder roller (equivalent to a transfer roller), and the transfer material is wound around the impression cylinder roller and passed through a nip between the impression roller and a drum-shaped intermediate transfer body (i.e., an image carrier), whereby the image is transferred onto the transfer material. According to such a configuration, the transfer material is passed through the nip while being mechanically held. Therefore, there is no possibility that the transfer material will adhere to the image carrier even when strong transfer pressure is applied in the nip.
In the image forming apparatus disclosed in Patent Document 2, an image that has been made visible by liquid development on a photoreceptor undergoes a primary transfer to an image carrier belt in the form of an endless belt (or a ring shaped belt), and the transfer material is passed through the nip between the image carrier belt and a secondary transfer roller. The image on the image carrier belt thereby undergoes a secondary transfer onto the transfer material. High transfer pressure is expected to be applied without allowing the transfer material to adhere to the image carrier belt when the transfer roller having the holding part described in Patent Document 1 is used as a secondary transfer roller in this apparatus.
Japanese Translation of PCT International Application No. 2006-513883 (e.g., FIGS. 1 and 2A) in an example of the related art (hereinafter Patent Document 1). Japanese Laid-open Patent Publication No. 2009-036943 (e.g., FIGS. 1 and 4) is another example of the related art (hereinafter Patent Document 2).